1. Field of the Invention
The present invention relates to a laser display apparatus, and in particular to a laser display apparatus which comprises a plurality of laser diode devices for scanning laser light, and a condensing unit having a scanning unit for reflecting laser light so that a certain image is displayed on a screen, and laser light is scanned in a two-dimension method using two scanning units, with the scanning units being designed to directly project laser light generated by a laser diode array on a screen for thereby displaying images.
2. Description of the Background Art
A projection type display apparatus such as a LCD is manufactured with a light and compact size, and a large size screen can be advantageously constituted using the same. However, a manufacturing price is high, and light loss increases due to the use of a polarization panel. A laser display apparatus has been developed as a new apparatus based on a light scanning method which uses a laser diode as a light source.
FIG. 1 is a view illustrating a construction of a conventional laser display apparatus.
As shown therein, a laser display apparatus comprises first through third lasers 11, 21 and 31 for generating and scanning red, green and blue wavelength lights, a light integration optical system 40 for integrating the lights scanned by the first through third lasers 11, 21 and 31, and a light scanning unit 50.
The light integration optical system 40 comprises a full reflection mirror 41 for reflecting red wavelength light scanned by the third laser 31, and first and second two-color mirrors 43 and 45. The first two-color mirror 43 transmits the light reflected by the full reflection mirror 41 and reflects the green wavelength light scanned by the second laser 21.
With the above operation, the reflected green wavelength light and red wavelength light are integrated with each other. The second two-color mirror 45 reflects the light inputted from the first two-color mirror 43 and transmits the blue wavelength light inputted from the first laser 11, so that the light integrated with red, green and blue colors transmits through the same path.
The first through third condensing lenses 13, 23 and 33 and the first through third light modulators 15, 25 and 35 are arranged at the transmission path of the light scanned by the first through third lasers 11, 21 and 31. Here, the light scanning unit 50 includes a rotation polygon mirror 51 which linearly scans light inputted, and a galvano mirror 55 which scans the linearly scanned light again based on the plane shape scanning method. The light scanning unit 50 scans the light integrated by the light integration optical system 40 based on the plane shape scanning method for thereby displaying images.
However, since the sizes of each laser 11, 21 and 31, which form the conventional laser display apparatus, is too large, such lasers cannot be adapted to a small size display apparatus which is engaged at a cellular phone or a portable watch. For example, since the width D1 between one end of the first laser 11 and the third laser 31 is about 450 mm, it is impossible to produce a small size display apparatus.
As the prior arts of the present invention, there are the U.S. Pat. No. 5,166,944 (Advanced laser technologies) and the U.S. Pat. No. 6,154,259 (Photera Technologies).
As another prior art of the present invention, a rotation polygon mirror, which is used at a scanning unit of a laser display apparatus, is constituted by attaching multiple mirrors at a side of the circular member. In the U.S. Pat. No. 6,154,259, 1350 micro laser arrays are used as the R, G and B light sources. As shown in FIG. 2, multiple polygon mirrors having different tilted angles are disclosed. As shown in FIG. 2, the rotation polygon mirror 70 is constituted by attaching a plurality of tilted mirrors having constant tilted angles in the direction of a center axis 71. In the U.S. Pat. No. 6,154,259, since the polygon mirrors 72 having different tilted angles are constituted so that the tilted angles of the neighboring mirrors are getting more different, whereby the production of the same is very difficult and the production cost is very high.
In the Korean patent laid-open No. 2004-90901 (image display apparatus having a two-dimension light scanning apparatus), there is disclosed an image display apparatus which has a two-dimension light scanning apparatus which scans light by deflecting light in a two-dimension method using two scanning units. However, the above image display apparatus uses a single laser light source, so that the time required for expressing pixels during a horizontal scanning operation is too short, whereby it is impossible to express multi-level images. In addition, the above Korean patent laid-open No. 2004-90901 should use a high power laser device.